I. Field of the Invention
This invention relates to workpiece manipulating systems having the ability to observe a workpiece with a television subsystem and more particularly to a method of and apparatus for generating transformation factors for translating measurement in the vision coordinate system to equivalent measurements in the manipulator coordinate system.
II. Description of the Prior Art
A variety of commercially available workpiece manipulators exist which are capable of grasping a part and moving it through three-dimensional space by means of coordinated motions along separately controlled axes. It has recently been proposed that such systems be equipped with optical-electrical image converter systems and means for analyzing the output of the image converter to determine the outline and location of a part within a field of motion of the manipulator. Outputs of this vision system may be used to control the manipulator and to inspect and identify parts to be manipulated.
Since the measurements of position and distance made by the vision system will inherently differ from equivalent measurements made by the manipulator sensors because different measurement scales are used in the two systems, it is desirable to provide means for converting signals representative of positions and distances as generated by the vision system into signals representative of the same measurements in the manipulating system coordinates. While the necessary conversion factors might be determined on a a priori basis from a knowledge of the parameters of the two measurement systems, in practice it is found that both systems exhibit some instability over a period of time and this drift reduces the accuracy of such calculated transformation parameters. Moreover, it may be desirable to separately support the vision and manipulation systems so that the two do not share incidental motions caused by support vibrations and the like. Also, it may be desirable to reposition the vision system relative to the manipulation circuitry from time to time which would require a recalculation of the conversion factors.